Paramedics involved in emergency or urgent patient transfers to hospitals should have completed the handover in 30 minutes, and be ready to take the next 999 call.

However, a new survey by the HSE of delays over six months last year showed overcrowded emergency departments left ambulances held up because their patient was admitted to hospital - but had to stay on their trolley because there was nowhere else to put them.

An analysis of 473 of delays showed Beaumont and the Mater hospitals in Dublin accounted for nearly half the occasions the ambulances were held up.

The problem was also serious in Cork University Hospital, Letterkenny Hospital in Donegal and University Hospital Waterford and University Hospital Limerick.

A breakdown of the times found that 85 ambulances could not leave the hospital for up to four hours while two spent up to seven hours at the emergency department.

In some cases "clinical need" was cited at a reason for the delay. Hospitals should have an escalation policy in place if ambulances are delayed which would involved opening wards to accommodate the patients.

The figures showed the ongoing knock-on effects of the trolley crisis on other parts of the health service. Overcrowding has risen in recent weeks.

The latest figures came as Health Minister Simon Harris ruled out reopening the emergency department in Nenagh Hospital, despite severe overcrowding in Limerick Hospital so far this autumn.

He said the smaller hospitals' framework, published in 2013, defined the role of Ireland's smaller hospitals.

"It outlines the need for smaller hospitals and larger hospitals to work together within hospital groups; the reorganisation of hospitals into more efficient and accountable hospital groups will ensure that all hospitals play a vital role in service delivery."

Increased funding will be given to the hospitals' group next year to facilitate the opening of a new emergency department.

The detail of the additional funding will be set out in the HSE's National Service Plan 2017, he said.